Improved machine for dressing millstones



MUMFORD & WALLIS.

Dressing Millstones.

No. 90,461. H Patented May 25, 1869.

N. PETERS. Pmw-mmmpmn waarnemer o. C,

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WICH, ENGLAND.A

Letters-Patcnt No. 90,461, dated May 25, 1869.

IMPROVED MACHINE FOR DRESSING MILLSTONES.

The Schedule referred to in these Letters Patent and making part of the same.

To all whom 'it may concern.-

Be it known that we, SAMUEL PRETTYMAN MUM- tonn and J om: WALLIS, of Greenwich, in the county of Kent, in that part of Great Britain called England,

have invented anew and improved Mode ofand Appa ratos for Dressing Millstones; and we do hereby deof supporting our apparatus when applied toa bedstone.

Similar letters of reference indicate like parts.

According to our invention of an improved mode of and apparatus for dressing millstones, instead of dressing the face ot' the millstones in a series of straight lines, arranged in the wellknownl manner, we make, on the working-face, a series of curved lines, arranged as a convolute, starting from the eye, or near the centre of the millstone, and terminating near the periphery. f

Our improved apparatus consists of a central shaft, b, which may be rotated in any convenient manner, on to which is keyed, or iirmly secured the longitudinal lever-frame c, which carries the slide-rest d, and cutting-tool holder e, shown detached on an enlarged scale.l l

The cutting-tool which we prefer to use in carrying out our invention, is a diamond, or other hard stone or stones, set in a holder, such as that shown at iig. 3, and hereafter more particularly described.

This holder is secured, in any convenient manner, in the tool-holder or slide-rest (l, mounted in the longitudinal frame c.

The central spindle b rests in a step, f, and this step is secured by screws to a centre-pin in the eye or near the centre of the millstone.

, The longitudinal frame cis made long enough to, admit of the slide-rest or holderfl being moved radially from the centre to the periphery ofthe millstone.

The slide tl, with the holder e of the cutting-tool,

. is made to move on guides c c in the frame c., whereby it is kept steady, and the holder e retained in a vertical position .i

Along screw, g, fig. 1, asin slide-rest of an ordinary lathe, passes through a female screw tapped in the rest or tool-holder d, so that by turning the screw g, by means of the handle g', at its outer end, the rest or tool-holder d of the tool may be moved along its guides c c', in a radial direction from -the central part or eye of the millstoneA, when the apparatus is in'its proper place on the stone.

1n order to dress the stone, the longitudinal frame c, with the rest or tool-holder d, and tool secured i therein, is moved round the central step, secured within the eye of the millstone, and the diamond or cutting-tool e being made to press on the face of the stone, will cut into the stone a curved line all round, as shown at a al a, iig. 2.

Stud-pins or stops are xed at any convenient point, either just outside the periphery of the millstone, or on the foundation-plate of the step f f, as shown at Ai t', figs. 1, 2, and 4.

A tappet-wheel, j, on the end ofthe screw y of the slide-rest, comes against these studs or pinsevery time the lever-arm and tool-holder are brought round to them, and thus the screw y is caused to turn on its axis, and thereby to move the rest 0r tool-holder cla short distance along its guides ofc', so that on the succeeding revolution of the apparatus round the central step f, the cutting-tool e will be made to operate upon a fresh part of the stone.

It will now be understood that every time the cutting-tool comes round to cit-her of the lixed pins or studs, it will be shifted a little further from the centre of the stone, and will thus be made to cut a convolnte curve in the face of the millstone.

An important feature of the invention is the mode of securing the diamond in the holder.'

The method we employ for effecting this object will be best understood by referring to the detached view of the holder, tig. 3.

The shank of the liolder consists of a square stem of iron, half of the lower end of which is removable,

-as shownat k, tig. 3, but' when in its place, is secured by screws l l. V

A hole, m, is drilled up the end of the tool, and is lilled with -a soft metal or alloy, divided in two parts,

such as is used for the bearings of machinery, and consists of 'a mixture of tin, zinc, and antimony;

In order to secure the diamond in its setting, the part k is removed, and after making a nick or recess in the lower end of* the soft-metal setting, the diamond is placed therein, and the two parts of the holder screwed together, so as to nip the diamond between the two pieces of soft metal, as shown at tlg. 3.

rI he faee's, both of the runner and the bed-stone, are dressed in the same manner, and, if desired, the central pin or pivot, round which the frame is made to rotate, may be placed eccentrically in either one or both stones, so that the convolute lines on the faces of the stones will be made to intersect or cross each other when the stones are at work.

Figs. 1 and 2 represent the apparatus adapted to the top stone or runner, but in order to adapt the apparatus to the bed-stone, a somewhat dilerent description of step must be made for the central spindle b. This modification-is shown in the sectional view, g

4, in which the step j fits over a, Acentral pin, h, of the bed-stone. It willbe seen that the step is provided with adj ustngscrews, for' the purpose of adjusting its position and ixing it.

Having thus described our invention, v

i' We claim as new, ztd desire to secure by Letters Patent- Thelimprovedmillstone-dressngmachine, composed 4of the ivertical shaft b, arranged to rotate in the vertica axis of the stone, and i'nowfided with them-1n G and sliding tool-holder, actuated as set forth, all substantially as and for the fmrpose set forth. 1

The above specification of our invention signed by us, this 19th day of June, 1868.

S. P. MUMFORD. JOHN WALLIS.

Witnesses: I

FRED. WALKDEN,

66 Chancery Lane, London. M. WYNN, C

'24 Royal Exchange, London. 

